The two blocks on the back of the boat are for the t-foil control. I think the go out to cleats near the deck/rack connection.
The rope connects from these blocks to 2 more blocks that are on pin. The rope thengoes to the tiller and sets the position (via ab 8:1 or 16L1 cascade). Those photos spark a memory of all the ropes being below the tiller. The slider inside just becomes the thing to keep it all in line.
I think there were 3 blocks on the pin, 2 for the control line and the other for a cascade. The key is that the rope pulls the tiller so the pin tries to move forward. A "Lots" to 1 ratio here helps find a setting - although that foil has a wide sweet spot
That foil always tries to pull to negativem so a bungee also acts as a pull in that direciton.
If the blocks are 8mm Allens, they can actually sit on the pin, meaning the system does not put more foil when you steer